The printmaking processes of planograpy work on the principle that grease and water do not mix. The artist employs a metal matrix, made of zinc or aluminum, and draws on it using a greasy substance known as ruche. The ruche retains ink or pigment and repels water, while the remaining surface area accepts water, producing a clean or blank background.

The matrix is sponged with water to keep the ungreased surfaces free of ink. A large heavy roller is then used to ink the plate. Only the greasy or drawn on surfaces retain the ink. Once the artist is satisfied with the amount of ink applied to the image, a paper or another substrate is placed on the matrix and both are run through a lithographic press. In the case of prints with more than one colour, a separate plate is prepared for each colour. Careful registration is of great importance – for each colour the plate must be exactly the same size and perfectly aligned to the original ‘plate mark’ created from the first passage through the press.

This process on planographic printing is known as lithography. Alois Senefelder invented the method of lithography in 1798, in Austria. By 1848, the same process had progressed to a point where it was possible to produce about 10,000 prints per hour. Jules Chéret (1836-1933) was the first person to mass-produce posters using this technique. His very first poster was called Orphée aux Enfants (1858). In 1889, Chéret was awarded the Legion of Honor for creating a ‘new branch of art’.

Early examples of lithography may be found in the work of French artists Eugéne Delacroix (1798-1863) and Théodore Gericault (1791-1824).

Chromolithography is a term used to describe coloured lithographs, in which each colour in the design is worked onto a separate plate or matrix and the paper is pressed against each of these matrices, to form the final design. In 1837, Godefroy Engelmann, a French lithographer based in Paris, patented a method of reproducing coloured images. In this method, a coloured image is filtered down to the three primary colours (red, blue and yellow), and each of these is printed one at a time, creating layers on the same substrate that overlap to create the desired tones. Initially this process was limited to a minimal range of colours, but by the end of the 19th century, specially manufactured inks provided the artist with an extensive palette of tones, making it possible to create the effect of light and shade.

Oleographs developed from chromolithography and became very popular towards the end of the 19th century. The process used was the same, but the inks used were extremely oily and differed in texture. When heavily varnished, the effect of an oleograph was almost identical to that of an oil painting. Even today, it is difficult to differentiate between the two.

Some examples of Indian artists who have used planographic printmaking techniques include Ramkinkar Baij, Somnath Hore, M.F. Husain, Tyeb Mehta and V.S. Gaitonde. Raja Ravi Varma’s oleographs are well known all over the world.

With the development of rotary presses and flexible rubber plates, the process of lithography has come a long way. Today, offset lithography is the preferred technique of producing high volumes of a single image, as well as limited edition prints. In this process, the image is first taken from the plate using a rubber roller, which then transfers the image onto the substrate.